This invention relates in general to adzing apparatus of the type utilized to cut railroad crossties, wherein one or more adzing heads are rotated about a vertical axis and are moved along a railroad track and progressively cut the upper surfaces of the railroad crossties for the placement of rails along the crossties. Each adzing head includes a plurality of cutting bit assemblies which are rotated by the adzing head in an orbit about the vertical axis. The cutting bit assemblies each include an annular cutting bit made of hardened metal or other hardened material which engages and cuts into the crossties. More particularly, the invention relates to an adzing bit assembly for mounting to an adzing apparatus which includes an annular cutting bit that has an annular cutting edge that is protected by a disk-shaped cutting bit shield and which is made of softer material than the cutting bit, and which wears away during use of the adzing head so as to progressively expose the cutting edge of the bit.
In the maintenance of railroads, it is customary to prepare the crossties of a rail bed by cutting the crossties to form grooves or seats in the ties for the reception of rail chairs which support the rails. Because of the particular configuration of the seats that must be formed in the crossties, special cutting tools have been utilized that are capable of rapidly cutting the ties with seats of the proper dimension. U.S. Pat. Nos. 3,005,479 and 3,486,542 disclose prior art adzing devices that have been developed for this purpose.
The cutting bits of the adzing heads used to cut rail seats in crossties usually are disk-shaped with a central opening through which a bolt or other connector extends. The cutting bit is made of hardened material, and usually is supported on its opposite parallel surfaces by various washers, bolt heads, and bushings. In order that the cutting bits last for a long time, it is desirable that they be fabricated of very hard material; however, the very hard materials are brittle and are subject to becoming chipped or cracked during use.